In U.S. Pat. Nos. 3,923,381; 3,957,031 and 4,002,499, examples are shown of a particular type of radiant energy concentration and collection device which is generally known as a "trough-shaped non-imaging collector". Such devices take radiant energy which strikes an entrance aperture and concentrate it onto an exit aperture having an area which is smaller than that of the entrance aperture. Reflective side walls of particular contour extend between the entrance aperture and the exit surface. An energy absorber is generally positioned adjacent the exit aperture.
The prior art methods of constructing a trough-shaped collector include the use of extruded aluminum side walls, aluminum sheet rolled into proper contour, or thick metalized solid plastic substrates. Each of these methods were characterized either by their high cost of manufacture or their extreme weight.
U.S. Pat. No. 4,099,515 attempted to overcome some of the prior art problems by utilizing a one-piece thin walled plastic substrate having wall portions corresponding to the ideal contour desired for such a trough-shaped collector. This device, as did its predecessor designs, required the use of concave reflector members.
A further problem existing in the design of several prior art devices arises from their inability to readily adjust the angle of reception to accomodate solar migration, that is, the relative movement between the sun and the earth created by seasonal variations. Thus, each of these devices required additional energy consuming means to tilt the collector and track the movement of the sun in an attempt to overcome the angular inefficiencies created by solar migration. These devices were generally predicated upon the premise that the 23.5 degree inclination of the equator required a collecting system to tilt in a north-south plane through an angle of 47 degrees in order to accomodate the seasonal change and thereby operate efficiently.
In addition, the traditional bias toward the utilization of concave reflectors is challenged herein by a design which employs a myriad of convex reflectors strategically disposed upon a uniquely designed elongated trough to maximize the collection and hence the concentration of the solar energy received therewithin.